1. Field of the Invention
The present invention relates generally to tension control systems, and more particularly is an improved tension control mechanism for a continuous winding machine that utilizes wireless or wired embedded closed loop feedback systems.
2. Description of the Prior Art
Coil winding technology has existed for quite some time in various fields. For example, the textile industry has long used winding methods to spool threads and yarns. Some examples of references in this area are the “Method and Apparatus for Winding a Thread on a Bobbin at a High Winding Speed” by Hori, et al., U.S. Pat. No. 4,059,239, issued Nov. 22, 1977; “Winding Apparatus” by Davies, U.S. Pat. No. 4,538,772, issued Sep. 3, 1985; and the “Operation Controlling Method for Textile Machine” of Matsui, et al., U.S. Pat. No. 4,984,789, issued Jan. 15, 1991. Another large subset of winding machines is directed to the art of coil winding for electric motor armatures. See, e.g., “Wire Tensioner for a Wire Handling Machine” by Hongo, et al., U.S. Pat. No. 5,080,295, issued Jan. 14, 1992.
A newer area for the application of winding technology is in the medical devices field. Catheters and stents are constructed by wrapping fine wires around a central mandrel. Current technology catheters and stents require the use of very fine wire filaments wrapped around proportionally small mandrels with winding angles that must be very accurately controlled. The very small diameters of the elements involved and the tight tolerances required make it difficult for current art equipment to construct the coils to the required specifications and without breakage.
One disadvantage of the prior art devices is that they typically use only one-way feed friction control, which produces filament tension that varies with feed rate. While this methodology is acceptable for applications using relatively large filament sizes, for the smaller filament sizes required in, for example, current art medical devices, the forces involved in commonly used feed rate control techniques are not acceptable The force necessary to control the feed rate is greater than the filament can withstand, so that breakage occurs.
Another disadvantage of the prior art devices is that the non-distributed control systems are too large and require too many control wires to enable an independent filament dispenser to spin around a mandrel, as continuous winding requires. The communication required to process information from the sensors to drive the necessary control motors in the machines controlling computer cannot be interrupted.
A further disadvantage of prior art systems that use control systems separate from the filament dispensing control is that multiple slip rings are required to operate with the supply spools rotating around the mandrel. The slip rings wear out quickly, and create debris that is unacceptable in cleanroom environments.
Accordingly, it is an object of the present invention to provide a continuous winding machine with embedded, closed loop tension control to enable production with much finer filament sizes and to tighter tolerances than is possible in prior art systems.
It is another object of the present invention to provide a winding machine that can be operated by both wireless data and wired data control systems.
Yet another object of the present invention is to provide a system that can be programmed for multiple winding parameters, and to provide a system in which the programming can be accomplished remotely.